The letters are NPA. It's short for no party affiliation, for voters who refuse to label themselves Republicans or Democrats because they do not identify with either party.

They are deserting the two major parties in droves, mostly in South Florida and in greater Orlando, and many are young and Hispanic.

Far outpacing both parties, they are the fastest-growing segment of Florida's electorate, but they are a sleeping giant.

Many of them don't vote, and some are so turned off by the negative tone and extreme partisanship of politics that they have no interest in voting.

"Someone would have to do something very powerful and moving to make me think that it's worth my time," says Alexis Aponte of St. Petersburg. "I reserve my right to register to vote. But I won't be forced to make an uninformed decision."

Aponte, a sign language interpretation student at St. Petersburg College, said it's hard to take politics seriously.

"It sounds like a joke," Aponte says. "I heard they were arguing about a fantasy football league at a presidential debate."

In South Florida, Luis Moreno Jr. of Miami Gardens signed up to vote in July with no party affiliation. Born in Cuba, naturalized as a U.S. citizen and a recent homeowner starting a family, he said a voter card helped him establish residency and he got one when he applied for a new driver's license.

"I don't really follow politics," Moreno says. "I think it would be ignorant to choose one party over another if I'm not following it."

The face of Florida voters

Aponte, 28, and Moreno, 27, are the human face of Florida's surge in no party voters, often described as independents.

More than one of every five no-party voters in Florida is listed as Hispanic. The actual figure is probably much higher because voters do not have to list race or ethnicity on a registration form, and many don't.

The 3.2 million people who avoid both major parties now are 27 percent of all Florida voters as Republicans and Democrats continue to lose political ground in America's biggest battleground state.

Two decades ago, 47 percent of Florida voters were Democrats and 41 percent were Republicans.

With the continuing rise of no-party voters, Democrats now make up 38 percent and Republicans 35 percent, but Republicans control two-thirds of the 160 seats in the Legislature.

When NPAs are combined with a much smaller pool of minor-party voters, they outnumber Republicans in the three most populous counties of Miami-Dade, Broward and Palm Beach, along with Orange and Osceola on the I-4 corridor in Central Florida. They eclipse Democrats in seven counties: Clay, Collier, Lee, Martin, Okaloosa, St. Johns and Santa Rosa. Many are first-time registrants who sign up to vote when they apply for a Florida driver's license under the federal "motor voter" law. Tax collectors and license clerks must provide voter registration forms to their customers.

'The game is rigged'

As they track the explosive growth in NPA voters, political experts in both parties are troubled by the implications.

One reason is that Florida is a "closed primary" state where only Republicans and Democrats can vote in most party primary contests, including a presidential preference primary next March 15. As a result, NPA voters find themselves walled off from the political system, effectively disenfranchised in primary elections.

"A group that is already passive has even less incentive to vote," said Matthew Isbell, a Democratic political consultant.

Lissette Rojas, 17, a student at Sickles High in Tampa, pre-registered as a no-party voter at a school voter drive even after Hillsborough elections workers told her she could not vote in a party primary.

"I don't like it," Rojas says. "I still have opinions. I want to be able to vote for who I want to vote for."

But she can't, and that's not likely to change.

The Legislature could make Florida an open primary state, but neither party has shown an interest in a change that would further dilute its influence.

"It's taxpayer-subsidized disenfranchisement," says Glenn Burhans Jr., a lawyer leading a statewide grass roots petition drive to make Florida an open primary state. "The game is rigged against non-affiliated voters. If they want to vote, they are being forced to associate with a group they don't want."

In Florida, all voters can vote in a primary if only one party has candidates, but a persistent loophole allows a write-in candidate on the ballot to "close" a primary, again shutting out NPA voters.

For two decades, lawmakers have repeatedly defeated efforts to close the loophole, which is often exploited by candidates maneuvering for a political edge.

For those who want to be NPA voters, county election supervisors advise them that they will be blocked from casting ballots in many primary elections.

"Florida is a closed primary state," reads a postcard that Clay County Supervisor Chris Chambless distributes to new voters. "If you choose a minor party or no party affiliation, you are allowed to vote only for non-partisan candidates and referendums in the primary."

A lack of competition

Party primaries historically draw poor turnouts in Florida, but the outcomes are frequently decisive, especially in races for the Legislature.

Florida's history of politicizing the drawing of legislative districts, combined with the Republicans' overwhelming advantage in fund-raising, has resulted in a lack of true "swing" districts where both parties are equally competitive and every vote is critical.

As a result, competitive races for the Florida House usually are in low-turnout primaries that are off limits to NPA voters.

For example, in the 2014 election cycle, seven House seats were decided by Republican primary voters. All seven nominees had only write-in or minor-party opposition in November.

Democratic consultant Isbell says that as partisan voters make up a shrinking share of the total electorate, primary turnouts will get smaller and candidates in primaries will be forced to take increasingly extreme positions to appeal to the most vocal elements of their party.

Republican Marian Johnson, senior vice president of political strategy at the Florida Chamber of Commerce, agreed.

"What's going to happen for the general election is that you're going to send people out of the primary who can't get elected," Johnson said.

Citing a dearth of data about no-party voters' preferences, the chamber will extensively poll 1,000 of them, Johnson said.

Staying home

State and county voter turnout data shows that no-party voters are less likely to vote than Republicans or Democrats in statewide and local elections.

In Miami-Dade, NPAs are 29 percent of the county's voters, but they cast 20 percent of the votes in the 2014 general election. If more of them voted, they could quickly alter the makeup of the county's Tallahassee delegation.

Miami-Dade has three state House districts where the combination of no-party and minor-party voters outnumber both Republicans and Democrats. It's a trend that's likely to be repeated in more districts in South and Central Florida in advance of the next remapping of districts in time for the 2022 elections.

The Miami seats are held by Republican Reps. Carlos Trujillo and Jeannette Nunez and Democrat Jose Javier Rodriguez.

"Representing a district that's right down the middle is great," says Rodriguez, whose constituents live in parts of downtown Miami and Coral Gables and the village of Key Biscayne. "People are just disaffected by the hyper partisanship coming out of Washington."

The nation's leading Hispanic advocacy group, the nonpartisan National Council of La Raza, says what's happening in Florida should be an urgent wakeup call to both political parties.

"They need to speak about how their candidates will serve the aspirations and concerns of these voters," said La Raza's deputy vice president, Clarissa Martinez.

She said "dog whistle politics," such as intensely partisan talk about immigration, will discourage unaffiliated Hispanics from voting because it makes them feel "demonized."

No-party voters dislike excessive partisanship and are more likely to be motivated by an issue such as the environment, education or growing the economy.

John Dunnigan, 23, of St. Petersburg, a USF student who works three part-time jobs, is a no-party voter. He said he tends to favor Democrats and that the issue that motivates him most is public education.

"I do plan to vote, but I don't want to lean one way or the other," Dunnigan said. "I like to be able to view each party individually."

Like other NPAs, Dunnigan is frustrated that Florida's closed primary system restricts his access to the ballot box.

"Just because you don't have a party affiliation doesn't mean you shouldn't be able to vote," Dunnigan said.

Florida has more than 12 million voters, and the state is expected to play a critical role in the 2016 presidential election. Along with its fast-growing and ever-changing electorate, Florida has been under a national microscope since the recount that decided the 2000 presidential race by 537 votes. In coming months, the Times/Herald will present "The Florida Voter," a series of in-depth stories examining the state of democracy in the nation's third most populous state.

There is a reason why the air in Tampa Bay is filled with playoff talk. If Thursday night's 12-8 Bucs preseason win over the Jaguars is any indication, it's also going to be filled with footballs thrown by quarterback Jameis Winston.